Recently, we have shown that the approach of depth sensitivity of magneto-optic ellipsometry can be
generalized to selectivity from different materials in nanostructures. We use the condition number as the figure of
merit to quantify the magneto-optic selectivity to two different magnetic contributions in magnetic nanostructure.
The method is demonstrated on nanostructures containing magnetically hard Fe particles in surface layer of soft
FeNbB amorphous ribbon. We separated both magnetic contributions from measurement of hysteresis loops using
magneto-optic Kerr effect in longitudinal configuration. Magneto-optic selectivity is discussed and theoretical
model on the basis of effective medium is compared with experimental data of longitudinal magneto-optic Kerr
effect depending on angle of incidence.